It is known that hair removal can be achieved with relatively high intensity light in order to achieve certain effects such as heat caused coagulation (i.e. denaturation) of certain portions (essentially proteins) of the hair cells leading to (temporal and/or permanent) hair removal (a.k.a. [temporal] hair growth reduction). Most known light based hair removal devices suitable for at least temporal hair removal make use of laser light sources or flash lamps as both light sources can provide high intensity light in short pulses. LEDs have generally been described as one alternative light source for skin treatment. Red hairs are usually not considered as being treatable with, e.g., IPL devices based on flash lamps, as red hairs don't comprise eumelanin, but rather the more reddish pheomelanin, which absorbs less energy in the usual overall IPL wavelength spectrum, so that a coagulation of relevant proteins of the hair located close to the melanin carriers via selective photothermolysis can't be easily effected.
Document US 2012/0116373 A1 discloses a light application apparatus for applying light to an object. The apparatus comprises a light source for generating processing light and sensing light, where a control unit controls the light source such that processing light in a processing time interval and sensing light in a sensing time interval are generated alternately. The light source is preferentially a solid state light source, in particular a light emitting diode or a laser diode. It is preferred that the light source comprises a VCSEL. The processing light preferentially has a wavelength in the range of 570-1200 nm and an energy density in the range of 2-30 J/cm2 and a pulse duration within 1 to 600 ms.
It is an object of the present disclosure to provide a hair removal device comprising a plurality of LED dies that is improved over the known devices and in particular provides red hair treatment capability.